European Pharmacopoeia (EP) Reference Standard Synonym(s): Ethyl (2 S )2-[(3 S ,5a S ,8a S , 9a S )-3-methyl-1,4-dioxodecahydro-1 H -cyclopenta[ e ]pyrrolo[1,2- a ]pyrazin-2-yl]-4-phenylbutanoate; Ramipril diketopiperazine Empirical Formula: C23H30N2O4...